1. Field of the Invention
The present invention generally relates to a radio wave receiving converter (LNB: Low Noise Block down Converter) for receiving a radio wave from satellite, and to an antenna device. More particularly, the present invention relates to a feed horn connected structure of a radio wave receiving converter, and to an antenna device with the radio wave receiving converter.
2. Description of the Background Art
In many LNBs, a body portion and a feed horn are integrated together. FIG. 15 shows a structure of a general LNB. As shown in FIG. 15, the LNB includes a body portion 1 and a feed horn portion 2. As illustrated in FIGS. 16A and 16B, feed horn portion 2 includes a first feed horn portion 2a on the side of body portion 1, and a second feed horn portion 2b. FIG. 16B illustrates an enlarged cross-sectional view of a region 21 of FIG. 16A.
In the conventional LNB, for some reasons relating to a fabrication of a mold for a body, a part of feed horn portion 2 was sometimes fabricated in a mold different from the one for body portion 1. In this case, first feed horn portion 2a and second feed horn portion 2b are connected together somewhere along feed horn portion 2.
First feed horn portion 2a and second feed horn portion 2b both have screw portions 11, and are connected together via screw portions 11. Through the application of a high-viscosity or pasty liquid sealing agent or an adhesive to gaps between screw portions 11 at this connected portion, air tightness between first feed horn portion 2a and second feed horn portion 2b is maintained.
The application of the liquid sealing agent or the adhesive to the screw portions 11 is, however, difficult to perform. In addition, operational variations could be large. Since a low-viscosity sealing agent or the like cannot be used, there is no other way but to utilize a high-viscosity sealing agent. Because of this, the sealing agent cannot smoothly get through to the little gaps, and an air can be easily entrained in the sealing agent. As a result, the air tightness may not be ensured.
An object of the present invention is to improve the workability regarding a connection of feed horn portions of a radio wave receiving converter, and to improve the reliability of the radio wave receiving converter by maintaining ensured air tightness at a feed horn connected portion.
Another object of the present invention is to provide an antenna device with a highly reliable radio wave receiving converter.
A radio wave receiving converter in accordance with the present invention is for receiving satellite broadcast. In one aspect, the radio wave receiving converter includes a body portion having a first feed horn portion, a second feed horn portion connected to the first feed horn portion, and a sheet sandwiched between the first feed horn portion and the second feed horn portion and maintaining air tightness at a connected portion of the first and the second feed horn portions.
By sandwiching the sheet for sealing between the first and second feed horn portions as described above, the air tightness at the feed horn connected portion can be maintained. As the sheet, a sheet with an adhesive is preferably used. As a result, by simply adhering the sheet to one feed horn portion and applying the other feed horn portion thereto, the sheet can be sandwiched between the feed horn portions. In addition, the air tightness at the feed horn connected portion can be improved.
An elastic body is preferably inserted between the above-described sheet and the first or the second feed horn portion. As a result, a force, which is to be developed when the second feed horn portion is screwed into the first feed horn portion, cannot be directly exerted to the sheet. Therefore, a breakage or a peeling of the above-described sheet can be avoided, and the adhesion of the sheet can be improved.
In another aspect, a radio wave receiving converter in accordance with the present invention includes a body portion including a first feed horn portion having a first screw portion, a second feed horn portion connected to the first feed horn portion and having a second screw portion screwed into the first screw portion, and a sealing portion provided at a region away from the first and second screw portions and maintaining air tightness at a connected portion of the first and the second feed horn portions.
Such a provision of the sealing portion at the region away from the first and second screw portions allows easier provision of the sealing portion, compared to the case in which the sealing portion is provided at the screw portion. For example, when a liquid sealing agent or an adhesive is used as a sealing agent, a low-viscosity liquid sealing agent or the like can be utilized, if a groove portion is provided and filled with the sealing agent or the like as described below. This facilitates the application or filling work of the liquid sealing agent or the like. In addition, through the use of the low-viscosity liquid sealing agent or the like, an air-void entrainment in the sealing agent or the like can be avoided, and the sealing agent or the like can spread all across the sealing portion.
The second feed horn portion described above may have an extension extending over an outer circumference of the first feed horn portion. In this case, the body portion has a groove portion receiving an end of the extension, and the sealing portion is provided in this groove portion. The sealing portion may include at least one of a sealing agent and a packing.
The sealing portion may be provided between the end of the second feed horn portion and a receiving portion on the first feed horn portion for receiving the end (a joint portion, a coupling portion, or an abutment portion with the second feed horn portion). In this case as well, the sealing portion can easily be provided, and additionally, an improvement in sealing can be obtained.
The groove portion may be provided at the receiving portion described above, and the sealing portion may be provided in the groove portion. In this case, the sealing portion includes at least one selected from the group consisting of an O ring, a packing, and a sealing agent.
The sealing portion described above may include an elastic body mounted to at least one of the end of the second feed horn portion and the receiving portion on the first feed horn portion. For instance, a resin, a rubber, or the like can be baked on a joint surface of the first feed horn portion joined with the end of the second feed horn portion, in order to form the elastic body.
In still another aspect, a radio wave receiving converter in accordance with the present invention includes a body portion including a first feed horn portion, a second feed horn portion connected to the first feed horn portion, a standing wall portion provided at the first feed horn portion and forming, in the first feed horn portion, a groove portion receiving a part of the second feed horn portion, and a sealing portion provided in the groove portion and maintaining air tightness at a connected portion of the first and the second feed horn portions.
In the present aspect as well, the groove portion is provided at the first feed horn portion, and the sealing portion is provided in the groove portion. Accordingly, a low-viscosity liquid sealing agent or the like can be utilized. As a result, as in the other aspects, the sealing portion can easily be provided, and additionally, an improvement in sealing can be achieved.
The sealing portion includes a sealing agent filled into the groove portion. In this case, a low-viscosity liquid sealing agent can be employed, and an improvement in sealing can be achieved in addition to the easier application of the sealing agent.
An antenna device in accordance with the present invention includes the radio wave receiving converter described above and a reflective parabolic portion reflecting a received radio wave and leading it to the radio wave receiving converter.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.